This invention relates to an improvement in a process for the production of a crude reaction product such as liquid phase methanol. More specifically, this invention provides a method of utilizing purge gas commonly associated with the synthesis stage of the overall process so as to improve the efficiency of the overall process.
A typical methanol synthesis process includes reforming, energy recovery, compression and synthesis reaction stages. A purge gas is normally removed from the synthesis reaction stage and then used as a fuel in the reforming stage. According to the present invention, the purge gas is initially passed through an expander to provide mechanical energy, then used as a fuel for production of electrical energy and ultimately used as a souce of heat to generate steam, preheat feed streams, or heat reactants in the reforming stage. Since this method uses the potential energy associated with pressurized purge gas as well as the chemical energy of the purge gas, more efficient use of the total energy associated with the purge gas is achieved.